The present invention relates to methods and apparatus useful in operations in a downhole environment, and in particular useful for operations in multi-lateral wellbores having a main wellbore from which multiple bores (laterals) extend or radiate.
Operations in multi-lateral wells are commonly run on coiled tubing and use a Multi Lateral Tool (MLT) to find the desired lateral leg of the well. Common operations for example include washing, cleaning out the wellbore, scale removal and stimulation. When a wellbore operation is required in a multi-lateral well, two separate operations must be performed. First, the desired bore must be found and entered using a MLT. The MLT operates at a high flow rate and a low pressure. As fluid is pumped through the MLT, the tool is manipulated in the well bore. When the end of the tool encounters a lateral, the fluid flow changes, and the associated change in flow pressure is detected at the surface. In response to this detection, the tool is then conveyed into the lateral for the desired operation. Then to perform many desired operations, such as cleanout, stimulation, or scale removal in the targeted lateral, a higher pressure is often required. However, the higher pressure required for the desired operation in the tool is often too great of a pressure at which to operate the pumping system. Therefore a shift in system flow rate and pressure is required between the steps of operating the MLT and performing the desired operation using the tool.